Racing: The mild-mannered look is not quite a lie, but the brain behind it is a steel trap

The Interview - Aidan O'Brien: Master of Ballydoyle has just revolutionised his yard in his quest for perfection. Sue Montgomery visits a true devil for the detail

In 1719, Louis-Henri de Bourbon, the seventh Prince de Conde of the blood royal, commissioned the architect Jean Aubert to design stables befitting his rank. Royal inbreeding in France during the 18th century being what it was, the Prince was a little eccentric in mind, believed he would be reincarnated as a horse and wanted to be housed in suitably magnificent style after his death. His luxurious 186-metre stable block, the Grandes Ecuries (which now forms the backdrop for the French Derby at Chantilly), took 20 years to construct and had enough stalls for the Prince and 249 of his fellows.

Modern subscribers to the theory of metempsychosis might wish to return as a colt under Aidan O'Brien's care. For the élite of the élite at Ballydoyle now live in a sumptuous palace of a yard, the brand-new nerve centre of the most successful private racehorse training establishment in the annals of the turf. From here, O'Brien will launch this year's attack on the world's top-level races, starting with the 2,000 Guineas at Newmarket on Saturday.

At 33, the quietly spoken Irishman has achieved more in 10 years than do many in a lifetime. But then, this golden corner of Co Tipperary has long been home to excellence and the new stable block is more than seven-star housing for the perceived 24 best colts in a given year, it is a statement of intent that the heritage of power and domination in what is a sport only on the surface is to be carried into the future.

The man whom O'Brien succeeded at Ballydoyle, his namesake but non-relation Vincent, did not fare badly from the yard he built in 1951, sending out the winners of 44 European Classics, including six Derbys. And the present incumbent, while not averse to making history, is superstitious enough not to want to interfere with it. "We wanted to modernise," he said, "and we thought of rebuilding, but you would not want to knock down where Nijinsky lived. You'd be afraid for your life to disturb the legacy of those old boxes. So we started from scratch." The result is the Iron Horse yard, named after Giant's Causeway, the tough, brilliant chestnut who won five successive Group One races in 2000.

Vincent paid £17,000 for his tranche of land; no figure has been volunteered for the cost of the new complex, though a guess would involve thinking of a figure and then adding three or four noughts. The result is a horseman's dream. Each high-ceilinged stable is 20ft square and contains two heat-lamps, a fluorescent light and an air- conditioning unit. Light and air flood in from fanlights, skylights and extra-wide doors at the front and rear of each box. The second door is to accommodate an unusual concept in a racing yard, for once the new grass area at the back of the boxes is established, each horse will have his own mini-paddock to mooch in and out of at will in fine weather.

Young beech hedges and sculptured plantings mark the boundary between walks of red and green non-slip rubberised paviours and the oval yard's grassy centre. Adjacent is a huge, airy, cathedral-like indoor ride a furlong in circumference.

But the point is, this is not just being flash. The training operation is one of twin peaks; it services the real money-spinner, neighbouring Coolmore Stud and its branches in Kentucky and Australia, by turning blue-blooded young colts into prospective stallions by their racecourse performance, and injury or disease could cost millions. Viruses are no respecters of lineage – one visited Ballydoyle last summer and another is rampant in Newmarket. Health and safety are paramount, and no chances have been taken with the fates either; the new boxes are numbered 1 to 12, and 12a to 24.

O'Brien – slight and bespectacled – looks an unlikely captain of industry. His style is the same as his legendary predecessor's, quiet and understated. His way is fatalistic – his favourite phrase is "God willing" – but it is engineered with meticulous planning and a mind like a steel trap.

Those who might think of belittling his success along the lines of, "Well, he's got the best horses" should note that he was breaking records before anyone had properly heard of him. After a spell with Jim Bolger, he became assistant to his now wife, Anne-Marie, and her father, Joe Crowley, before taking out his own licence in June 1993. He saddled two winners on his first day, became the first trainer to win 100 races in his debut season, set an earnings record for jumpers, netted five jump titles and was Ireland's champion amateur rider twice to boot. Bolger knew what manner of man was his young assistant; he later said that if marrying him would have kept him in the yard, he might have considered it.

John Magnier, Vincent's son-in-law and the owner of Ballydoyle and Coolmore, noticed too, and recruited O'Brien as trainer in 1995. His judgement has been vindicated in no uncertain terms with a plethora of Classics and a series of extra-ordinary feats. After the year of Giant's Causeway came the 2001 campaign, when O'Brien's horses won a world-record 23 Group or Grade One contests, including his first Derby with Galileo; last year he scored a one-two in both the 2,000 Guineas and Derby, and sent out Rock Of Gibraltar to complete a sequence of seven consecutive Group Ones, beating Mill Reef's 30-year-old record. He has been champion trainer in Britain for the past two years, the first based in Ireland to take the title since Vincent in 1977. And as well, there were Istabraq's three Champion Hurdles.

O'Brien will never be extrovert, but his shyness, even nervousness, in the company of strangers has disappeared. His 600-acre fastness is not a place you drop into unannounced, but the gates are now opened annually in the spring to the press and the host is confident, helpful, unfailingly courteous and patient, giving a considered reply to every question about any of his 130 horses. He is not known for sticking his neck out – he would need time to admit that yes, the world may indeed be round – but his attitude, no side, no smart-arsiness, would put many of his senior colleagues in this country to shame.

His acts to date will be hard enough to follow, but there is a sea change at Ballydoyle this year, the catalyst being the necessity of competing on the global stage with Magnier's rival stag, Sheikh Mohammed, whose Dubai-based Godolphin operation has achieved outstanding success with older, fully mature horses.

Perhaps it is a tacit admission that this year's three-year-old division lacks strength in depth, but High Chaparral, Hawk Wing and Black Sam Bellamy, all Group One winners, will be racing on as four-year-olds instead of being hustled off to stud. High Chaparral, winner of the Derby and Breeders' Cup Turf, is a particular coup for the racing public, only the fourth Epsom hero in 20 years to remain in training.

O'Brien welcomes the strategy, in the short and long term. "It will be an interesting challenge," he said. "High Chaparral was a sick horse last year after the Derby and I did not think he'd make it back in the autumn, but he is a hardy customer. He and Hawk Wing did not have an easy time, they danced to every beat, but the signals are right. They are pioneers for us; we're experimenting with the older horses, but if it goes well and we get them rolling it will mean that in future years we can take the pressure off the three-year-olds. The Derby will still be the most important race for us, but after that there will be some support from the older brigade if necessary. A change of emphasis will give us options worldwide. We've not had a runner in the Dubai World Cup early in the year, but in future it could be a viable possibility."

The first of the Classic generation to carry the Ballydoyle flag into battle will be Hold That Tiger in the 2,000 Guineas, with Yesterday the main contender for the 1,000 Guineas the next day. A good run in the Guineas will ensure a Derby tilt for Hold That Tiger. Also on course for Epsom are Brian Boru and Alberto Giacometti, plus later developers such as Catcher In The Rye and Balestrini.

O'Brien's heart is always at home, where he can watch and learn his horses and where he gains huge strength and delight from the normality of family life. His young son Joseph was his assistant at his latest open day, and the boy and his three sisters are regular talismans on big-race days in Ireland. And their father remains pragmatic about the pressure of playing at the top table. "I could blow these horses all I want," he said, "but words won't make them run faster. The racecourse is the test. God willing, they'll get where we want them and maybe be good enough, but all we can do is our best."

Biography: Aidan O'Brien

Born: 16 October 1969, Wexford, Ire

Family: married to Anne-Marie, children Joseph, Sarah, Anna, Donnacha.

Training career: first winner in June 1993. Irish champion jumps trainer 1994 to 1998. With Istabraq, won the Champion Hurdle from 1998 to 2000. Moved his Flat horses to Ballydoyle and finished second in the Irish trainer's standings in his first season, then won the title in 1997. In 2001 won 22 of the 78 Group One races in Europe, becoming the first overseas trainer to win the British trainers' title since Vincent O'Brien (no relation) in 1977. British champion again in 2002.

First Classic wins: Desert King (1997 Irish 2,000 Guineas and Irish Derby).